1. Field of the Invention
The present invention relates to an illumination module, and more particularly, to a light emitting diode (LED) illumination module having a wide illumination range and a uniform illumination.
2. Description of the Prior Art
Currently, most streetlamps are mercury vapor lamps that are disposed at the roadsides to provide illumination at night. The mercury vapor lamps have high power consumption, and thus the bulbs or tubes of the mercury vapor lamps will generate massive heat when used for a long time. In addition to the high power consumption problem, the lamps or tubes will burn or turn black, and this may cause damage to the whole lamp module. In addition, mercury itself is a pernicious material, and will hurt the human brain and nervous system, and therefore mercury should be handled carefully during recycling. Therefore, LEDs having the advantages of light weight, environmental soundness, single color light, low power consumption, and long life time can solve the associated problems of mercury vapor lamps such as power consumption, short life time, massive heat and high pollution.
Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a cross-sectional structure of an LED illumination module according to the prior art. As shown in FIG. 1, the LED illumination module 10 of the prior art includes a substrate 12, an LED 14 and a reflective lampshade 16. The LED 14 is disposed on the substrate 12. A sidewall of the reflective lampshade 16 is symmetric about a central line of the reflective lampshade 16, and surrounds the LED 14. Please refer to FIG. 2, which is a radiation diagram illustrating the angular distribution of light from the LED illumination module according to the prior art. As shown in FIG. 2, the angular distribution of light from the LED illumination module according to the prior art is between 30 degrees on the left-hand side and 30 degrees on the right-hand side through measuring the relation of the intensity and the angle of light from the LED illumination module. Therefore, the emitting angle range of the LED illumination module can be defined as substantially 60 degrees.
Please refer to FIG. 3, which is a schematic diagram illustrating the intensity distribution of light from the LED illumination module according to the prior art. As shown in FIG. 3, a simulated road has an x-axis and a y-axis. The LED illumination module 10 is disposed over −50 millimeters of x-axis and at the origin of y-axis of the simulated road. When the measured intensity of light of the distribution curve is 25 watts per square meter, the distribution curve of the light is between 150 millimeters and −50 millimeters of the x-axis and between 110 millimeters and −110 millimeters of the y-axis.
However, the LED illumination module has an insufficient illumination range at the y-axis of the road. A streetlamp and an adjacent streetlamp have a distance between them. When a part of the y-axis of the road illuminated by the light is short, the distance between the streetlamp and the adjacent streetlamp should be shortened. Therefore, more streetlamps should be used to illuminate the whole road, which will cause greater energy consumption. If the number of streetlamps is decreased, a distance of the road with no illumination between the streetlamp and the adjacent streetlamp will be generated because of the limit of the illumination range of the LED illumination module, which will result in more accidents.